Communication signals, such as those relating to voice or data, are generally transmitted along cables where each cable includes several individual lines for carrying different individual communication signals. Common communication cables include four, six or eight lines where each line carries a separate signal. When one or more of the signals transmitted over a cable fail to reach the destination, it is often important not only to determine which portion of the cable is defective, but which line within the cable is defective so that appropriate corrective action can be taken. Furthermore, at times it is beneficial to be able to characterize the type of line failure which is preventing the successful reception of a communication signal.
A cable testing system is presently commercially available for testing communication cables and pairs of lines contained therein. Specifically, the cable testing system includes a single main unit which is powered, and a plurality of remote modules which are not powered. The main unit has several indicator lights thereon and is controlled by a microprocessor. In contrast, none of the remote modules include indicator lights. Each remote module has an xe2x80x9celectronic addressxe2x80x9d which can be determined by the main unit. In other words, the main unit is able to distinguish one remote module from another. This will become more evident upon reviewing the following brief description of how this prior art cable testing system operates.
To test, for example, two cables, one remote module is connected to an end of a first cable, and another remote module is connected to an end of a second cable. Then, the main unit is connected to the other end of the first cable, and the main unit is operated to send signals along the cable to the first remote module. Specifically, the main unit sends a signal along a first line of the cable to the first remote module, and the remote module sends the signal back to the main unit along a second line of the cable. If the main unit does not receive the signal back along the second line of the cable, the main unit reports, using one or more of its indicator lights, that the first line pair has failed the test. The main unit repeats this process for each pair of wires in the cable (i.e. sends a signal along a third line of the cable, and then receives the signal back along a fourth line of the cable, etc.). After testing each pair of wires in the cable, the main unit reports, using the indicator lights, the results of the test such as the type of failure which has been detected and along which pair of lines within the cable the failure has been detected.
Additionally, as the main unit receives the signals back from the remote module, the main unit is able to determine, based upon certain characteristics of the signal received back from the remote module, which remote module is, in fact, connected to the other end of the cable. The main unit reports this identifying information using its indicator lights. For example, while the first remote module may have an xe2x80x9celectronic addressxe2x80x9d of xe2x80x9cAxe2x80x9d which can be identified by the main unit, the second remote module may have an xe2x80x9celectronic addressxe2x80x9d of xe2x80x9cBxe2x80x9d which can be identified by the main unit. Therefore, the main unit reports not only whether all the pairs of lines in a cable have passed the test, but also which particular remote module is connected to the other end of the cable which has been tested.
After the first cable has been tested using the main unit, the main unit can be disconnected from the end of the first cable and can be connected to the end of the second cable so that the second cable can be tested. As mentioned, a second remote module may have been connected to the other end of the second cable. Alternatively, the first remote module can be disconnected from the first cable and connected to the end of the second cable, opposite the main unit. To test the second cable and any subsequent cable, the same process is applied as was described above with respect to the testing of the first cable.
One disadvantage of the above-described cable testing system is that it effectively tests a cable by testing pairs of lines within the cable rather than by testing each individual line of the cable. Because the test signal is sent from the main unit to a remote module along one line of a pair, and returns to the main unit along the other line of the pair, it is only possible for the main unit to determine whether a defect exists within a pair of lines, as opposed to being able to determine which line of a particular pair of lines is actually defective. As mentioned, it is generally beneficial to be able to determine which particular line within a cable is defective so that appropriate corrective action can be taken. Additionally, because pairs of wires are tested, it becomes important to be able to determine the type of cable that is being tested (e.g. USOC, 10 Base T, Token Ring, etc.). Therefore, the above-described cable testing system includes a microprocessor in the main unit, and the microprocessor controls the testing of the cable.
Another disadvantage of the above-described cable testing system is that the remote modules cannot be used to test a cable without using the main unit. In other words, the remote modules cannot operate as stand-alone cable testers, and require the association with the main unit to test a cable. This is because it is the main unit which is powered, which has indicating lights, and which contains the microprocessor which controls the testing of the cable.
The present invention provides a cable testing system directed toward overcoming the disadvantages associated with the above-described prior art cable testing system.
An object of an embodiment of the present invention is to provide a line tester and cable testing system for testing the individual lines of a cable, as opposed to testing the lines of the cable in pairs.
Another object of an embodiment of the present invention is to provide a line tester and cable testing system for testing lines of a cable without having to employ a microprocessor.
Still another object of an embodiment of the present invention is to provide a line tester, such as a remote module of a cable testing system, which can operate as a stand-alone line tester.
Briefly, and in accordance with at least one of the foregoing objects, an embodiment of the present invention provides a cable testing system for testing individual lines of a cable. The cable testing system includes a main unit having an input jack and a plurality of identifying lights connected to the input jack, and at least one remote module. The remote module includes an input jack and an output jack, a power source in communication with the output jack, and a plurality of identifying lights connected to the input jack. Preferably, the output jack of the remote module is configured to receive one end of a multiple line cable and the input jacks of both the main unit and remote module are configured to receive the other end of the multiple line cable.
The remote module preferably includes a test signal generator which is connected to the power source and the output jack, and the test signal generator is configured to send test signals sequentially along each line of the cable. Preferably, the remote module also includes an identifying signal generator which is connected to the power source and the output jack, and the identifying signal generator is configured to send an identifying signal along a line of the cable. The identifying signal generator may include a signal generator which is connected to a line selector, where the line selector is set-able to specify which line of the cable the identifying signal is sent along. Preferably, neither the main unit nor the remote module includes a microprocessor, thereby reducing cost. Additionally, preferably the remote module can be used as a stand-alone line tester.